Anticancer chemotherapy and radiotherapy trigger both non-cell-autonomous and cell-autonomous death.

Even though cell death modalities elicited by anticancer chemotherapy and radiotherapy have been extensively studied, the ability of anticancer treatments to induce non-cell-autonomous death has never been investigated. By means of multispectral imaging flow-cytometry-based technology, we analyzed the lethal fate of cancer cells that were treated with conventional anticancer agents and co-cultured with untreated cells, observing that anticancer agents can simultaneously trigger cell-autonomous and non-cell-autonomous death in treated and untreated cells. After ionizing radiation, oxaliplatin, or cisplatin treatment, fractions of treated cancer cell populations were eliminated through cell-autonomous death mechanisms, while other fractions of the treated cancer cells engulfed and killed neighboring cells through non-cell-autonomous processes, including cellular cannibalism. Under conditions of treatment with paclitaxel, non-cell-autonomous and cell-autonomous death were both detected in the treated cell population, while untreated neighboring cells exhibited features of apoptotic demise. The transcriptional activity of p53 tumor-suppressor protein contributed to the execution of cell-autonomous death, yet failed to affect the non-cell-autonomous death by cannibalism for the majority of tested anticancer agents, indicating that the induction of non-cell-autonomous death can occur under conditions in which cell-autonomous death was impaired. Altogether, these results reveal that chemotherapy and radiotherapy can induce both non-cell-autonomous and cell-autonomous death of cancer cells, highlighting the heterogeneity of cell death responses to anticancer treatments and the unsuspected potential contribution of non-cell-autonomous death to the global effects of anticancer treatment.

Cytotoxic effect of lapatinib is restricted to human papillomavirus-positive head and neck squamous cell carcinoma cell lines.

BACKGROUND: Lapatinib is a dual epidermal growth factor receptor (EGFR) and HER2 inhibitor. Overexpression of these receptors is frequently observed in head and neck squamous cell carcinoma (HNSCC). As growing proportion of HNSCC is characterized by human papillomavirus (HPV) infection, we aimed at evaluating the efficacy of lapatinib as function of HPV status in HNSCC cell lines. METHODS: Two HPV-positive and two HPV-negative HNSCC cell lines were used. Proliferation, cell cycle, and Annexin V assays were performed to test their sensitivity to lapatinib. Combination of lapatinib and ionizing radiation was evaluated with clonogenic survival assays. Akt, EGFR and HER2, and E6/E7 expression and activation were analyzed by immunoblotting and quantitative reverse transcription polymerase chain reaction. RESULTS: Lapatinib reduced E6 and E7 expression and Akt phosphorylation, inhibited cell proliferation and induced cell death in HPV-positive cell lines. An additive effect of lapatinib with radiation was observed in these cells. Lapatinib had no effect on HPV-negative cells. CONCLUSION: Lapatinib efficacy restricted to the HPV-positive cells suggests that HPV status could be a potential marker for enhanced response to lapatinib in HNSCC.

Synergy of Radiotherapy and a Cancer Vaccine for the Treatment of HPV-Associated Head and Neck Cancer.

There is growing interest in the association of radiotherapy and immunotherapy for the treatment of solid tumors. Here, we report an extremely effective combination of local irradiation (IR) and Shiga Toxin B (STxB)-based human papillomavirus (HPV) vaccination for the treatment of HPV-associated head and neck squamous cell carcinoma (HNSCC). The efficacy of the irradiation and vaccine association was tested using a model of HNSCC obtained by grafting TC-1/luciferase cells at a submucosal site of the inner lip of immunocompetent mice. Irradiation and the STxB-E7 vaccine acted synergistically with both single and fractionated irradiation schemes, resulting in complete tumor clearance in the majority of the treated mice. A dose threshold of 7.5 Gy was required to elicit the dramatic antitumor response. The combined treatment induced high levels of tumor-infiltrating, antigen-specific CD8(+) T cells, which were required to trigger the antitumor activity. Treatment with STxB-E7 and irradiation induced CD8(+) T-cell memory, which was sufficient to exert complete antitumor responses in both local recurrences and distant metastases. We also report for the first time that a combination therapy based on local irradiation and vaccination induces an increased pericyte coverage (as shown by αSMA and NG2 staining) and ICAM-1 expression on vessels. This was associated with enhanced intratumor vascular permeability that correlated with the antitumor response, suggesting that the combination therapy could also act through an increased accessibility for immune cells. The combination strategy proposed here offers a promising approach that could potentially be transferred into early-phase clinical trials.